Telecommunication switches are provided in a network in order to direct data from one line to another. Typically, switches have a plurality of inputs and a corresponding plurality of outputs. Network lines can be coupled to each of the switch inputs and outputs, so that data carried on any input line can be routed to any output line. Networks do not remain fixed, however. Frequently, some lines are added, while others are dropped. Alternatively, data previously intended for one switch output line may be required to be shifted to another output line. In response to such changes, switches in a network must be appropriately reconfigured or rearranged. Moreover, the switches should be non-blocking, i.e., any input can be mapped or coupled to any output without any collisions or conflicts.
Non-blocking rearrangement algorithms are known which provide adequate rearrangement of a switch. Once such algorithm, known as the Looping Algorithm, requires that a switch be divided into stages of smaller 2xc3x972 switches. See J. Y. Hui, xe2x80x9cSwitching and Traffic Theory For Integrated Broadband Networksxe2x80x9d, Kluwer Academic Publishers, 1990, pp. 77-80. Routes through the switch originate at an input, and following a known methodology, pass through selected 2xc3x972 switches to a desired output. The route then loops back through an adjacent output to couple to a desired input. This process is repeated until each input is coupled to a desired output.
Although the Looping Algorithm is relatively fast, conventional switches, reconfigurable based on the looping algorithm, require a power of 2, i.e., 2n, physical center stages, where n is an integer. Each switch, however, occupies space and consumes power. Accordingly, in circumstances when a switch must conform to various spatial, as well as, power constraints, reconfiguration based on the Looping Algorithm may not be possible.
Consistent with the present invention, a switch is provided comprising a first stage having a plurality of first switch circuits, each of which including a plurality of inputs and a plurality of outputs. A second stage is also included having a plurality of second switch circuits. Each of the plurality of second switch circuits has a plurality of inputs, each of which being respectively coupled to one of the plurality of outputs of the plurality of first switch circuits. Each of the plurality of second switch circuits also has a plurality of outputs, whereby a number of the plurality of second switch circuits equals N, where N is any integer other than a power of 2. The switch further includes a third stage having a plurality of third switch circuits, each of which including a plurality of inputs and a plurality of outputs. Each of the plurality of inputs of the third switch circuits is coupled to a respective one of the plurality of outputs of the second switch circuits.
Both the foregoing general description and the following detailed description explain examples of the invention and do not, by themselves, restrict the scope of the appended claims. The accompanying drawings, which constitute a part of this specification, illustrate apparatus and methods consistent with the invention and, together with the description, help explain the principles of the invention.